Download Closed claims studies in anesthesia

Closed claims studies in anesthesia: A
literature review and implications for
practice
Meghan G. MacRae, RN, PhD
Rochester, New York
2006 Student Writing Contest Winner
Historically, closed malpractice claims have been used to
identify and examine potential causes for adverse anesthesia outcomes. In the United States, the American Association of Nurse Anesthetists and the American Society of
Anesthesiologists have compiled and analyzed such data.
In all claims filed, respiratory events were most common,
and the most common outcome class was brain damage or
death. These findings and others led to improved practice
standards, including end-tidal carbon dioxide and pulse
E
thical considerations preclude direct, prospective experimentation to quantify risks
and predict outcomes associated with differences in anesthetic practice. Prospective
nonexperimental studies become prohibitively expensive for rare events, such as anesthesia
incidents. Retrospective studies are, therefore, the
norm, as they are in most healthcare research.1(p188)
Random or comprehensive review of medical records
for rare events is generally impractical.2 Previously
identified anesthesia incidents, however, offer an alternative and concentrated data source for examination of
possible causes, precipitating events, and outcomes.
One such source is the closed malpractice claim.
This literature review will describe the 2 major US
databases of closed anesthesia-related malpractice
claims, summarize the findings of the database analyses, discuss limitations of using closed claims data,
identify practice changes precipitated by the analyses,
and suggest areas for further research.
History and review of literature
A malpractice claim is a demand for financial compensation for an injury resulting from medical care,3 and
it is closed when it has been dropped or settled by the
parties or adjudicated by the courts.4 In 1974, the
National Association of Insurance Commissioners
conducted the initial research using closed claims to
identify malpractice risks.3 At that time, anesthesiologists represented 3% of insured physicians but
accounted for 11% of the total dollars paid for patient
injury, and 90% of these payments involved care
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oximetry monitoring. Although some researchers have cited
closed claims studies as evidence of anesthesia risk trends,
the nature of the data makes it inappropriate for calculation
or comparison of risk. Further work is needed to elucidate
some mechanisms of injury and to develop interventions to
maximize patient safety.
Key words: Adverse outcomes, anesthesia risk, closed
claims, malpractice.
below the standard.2,5 Consequently, anesthesiaprovider liability insurance costs rose dramatically in
the 1980s.2,6 In 1985, the American Society of Anesthesiologists (ASA) started the Closed Claims Project
to improve patient safety and address rising insurance
costs by identifying the scope and cause of significant
anesthesia-related patient injuries.2,5,7-9 Because those
data primarily reflected physician providers, the
American Association of Nurse Anesthetists (AANA)
began examination of closed claims involving Certified Registered Nurse Anesthetists (CRNAs) and published its initial findings in 2001.3
The ASA Closed Claims Project (ASA-CCP) has
conducted annual reviews of anesthesia-related malpractice claims of the 35 participating insurance carriers.8,10,11 Hundreds of volunteer physician anesthesiologists have reviewed case files (typically hospital
records, anesthetic records, narrative statements of
involved personnel, expert and peer reviews, deposition summaries, outcome reports, and settlement or
award details) and recorded findings using a standard
data collection form.2 The database has been updated
annually with data collected and reviewed the previous year.8 At last report, the database contained data
for 6,894 claims9 representing events occurring since
1962.12 Posner4 categorized the data according to timing of the event that led to the claim: 12% from 1970
through 1979, 54% from 1980 through 1989, and 33%
from 1990 through 1999, most before 1995. These figures reflect the average 5-year lag time from event to
case closure.4,7
By contrast, the AANA closed claims database
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267
reflects 223 cases from a 1-time review effort by 8
CRNAs of the records of the St Paul Fire and Marine
Insurance Company.3,13 This insurance provider was
the “largest single insurance carrier for CRNAs”13 but
has since withdrawn from offering malpractice insurance.14 All cases represented in the AANA database
occurred between 1989 and 1997 and were closed
between 1995 and 1997.3,13
Both databases exclude dental claims, such as
chipped teeth, and cases in which an anesthesia
provider was named as a defendant but did not contribute to the adverse event or for which insufficient
data existed to reconstruct the basic sequence of
events or the nature of the injury.3,9 Although the data
collection tools have not been published, Petty et al10
reported the major instrument categories for each
database. Members of the ASA have limited access to
the data through standardized queries submitted to
the ASA-CCP.2,9,15,16 No access mechanism was identified for AANA data. Each organization has published
closed claims findings almost exclusively in its own
publications, ie, Anesthesiology, ASA Newsletter, and
AANA Journal.
• Overall findings. Published studies of anesthetic
morbidity and mortality date to at least 1858.3 Publications before closed claims analyses focused on
faulty judgment and drug-related errors as primary
causes and identified respiratory insufficiency, gastric
aspiration, and drug overdose as precipitating events.3
Because the cause is often difficult to ascertain from
closed claims data, recent researchers referred to
“events,” which appeared to herald or precipitate the
“outcome” or ultimate injury.
The ASA-CCP data for relatively recent incidents
(since 1990) reflected an outcome of death or brain
damage in 31% to 32% of all claims.4,7,17-19 This outcome was precipitated by a respiratory event in 45% of
these cases and, more specifically, was attributable to
inadequate ventilation (7%), esophageal intubation
(7%), or difficult intubation (12%).7,18 The percentage
of death or brain damage outcomes attributable to a
cardiovascular event was 25%.2 Nerve injury represented the second most common outcome at 21% of
all claims.4 Other outcomes reflected as a percentage
of total claims were airway injury (8%), burns (6%),
awareness or emotional distress (5%), eye injury
(5%), backache (5%), headache (5%), pneumothorax
(4%), aspiration pneumonitis (3%), and newborn
injury (1.5%).4
Initial AANA data analysis by Jordan et al3 showed
that CRNA-related incidents reflected an outcome of
death or brain injury in 44% of all claims. Of all
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CRNA-related claims, 39% reflected a contributing
respiratory event, and 68% of claims reflecting a respiratory event had a death or brain damage outcome.
Therefore, 61% of the reported CRNA-related death or
brain injury outcomes may be attributable to a respiratory event. Other findings by Jordan et al3 included
the following:
1. CRNA lack of vigilance was a contributing factor
in 79% of claims.
2. Worse outcomes were correlated with inappropriate care, lack of vigilance, preventable outcomes,
and respiratory or airway incidents.
3. Worse outcomes were not correlated with preoperative physical status, patient age, type of surgery or
procedure, type of anesthetic, age of anesthesia
provider, or year of certification of the CRNA.
4. When comparing CRNAs working with an anesthesiologist with CRNAs working without an anesthesiologist, there were no significant differences in outcome, injury severity, appropriateness of care,
adequacy of preinduction activities, vigilance of the
CRNA, preventability of outcome, use of pulse oximetry or inspired oxygen monitoring, or presence of a
contributing respiratory or airway incident.
In a novel analysis, Kremer et al20 studied the
AANA data for evidence of cognitive biases that might
have contributed to the outcome. Anchoring, hindsight bias, and use of the availability heuristic were
each evident and resulted in reluctance to accept the
seriousness of the situation or failure to consider the
full range of possible diagnoses. The most comprehensive interpretation of the data as a whole, however,
came from Crawforth21: “[Errors] were caused by a
multiplicity of factors. An individual may have placed
the proverbial ‘last straw’ on the adverse event, but in
no instance was the basis of any claim an isolated
action.”
• Sympathetic blockade and cardiovascular events.
Early analysis of the first 900 ASA-CCP claims
revealed 14 cardiac arrest deaths during spinal anesthesia.22 The precipitating events were thought to be
undetected respiratory insufficiency and sympathetic
blockade.22 Subsequent work by Thrush and Downs23
explained that if the sympathetic system is blocked by
a spinal anesthetic and a vasovagal reaction occurs, an
imbalance between the parasympathetic and sympathetic systems might be exacerbated in susceptible
individuals with increased vagal tone, an estimated
7% of the population. Cheney2 recommended administration of epinephrine early in resuscitation, and
Thrush and Downs23 recommended prophylactic
administration of atropine.
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Kopp et al24 found that in patients undergoing neuraxial anesthesia who had a cardiac arrest, the anesthetic contributed to 54% of the cardiac arrests. They
also found that survival rates after cardiac arrest were
higher for patients with neuraxial anesthesia (65%)
compared with general anesthesia (31%). This
research was based on a retrospective review of all
reported cardiac arrests during anesthesia at a single
institution, not on closed claims data.
The ASA-CCP data reflected an increase in the proportion of death and brain damage claims attributable
to a cardiovascular event from 13% in the 1970s to
25% in the 1990s; but this increase may simply reflect
the decreased proportion of claims attributable to a
respiratory event.2
• Respiratory events. Initial ASA-CCP analyses identified respiratory events as the single largest class
(34% of all claims).25 Respiratory events were associated with death or brain damage in 85% of those
claims.25 Inadequate ventilation was thought to be a
factor in 38% of respiratory event claims, and 72% of
these claims were thought preventable with better
monitoring.25 The findings were reinforced by Tinker
et al,26 who asserted that 93% of preventable incidents
could have been prevented with a combination of
pulse oximetry and capnometry. In 1990, pulse
oximetry was included in the ASA Standards for Basic
Intra-Operative Monitoring.27 Subsequent claims
showed that only 7% of the death or brain damage
outcomes were thought to be due to inadequate ventilation,7,18 and Cheney19 reported that inadequate
ventilation events leading to death or brain damage
decreased significantly when pulse oximetry was
used.
Larson and Jordan,28 in analysis of CRNA-related
claims, reported that 9% of claims for respiratory incidents involved endobronchial intubation, which was
thought to contribute to inadequate ventilation. Their
recommendation was for providers to be aware of tube
markings and recommended depths for common populations.
According to the early data analysis by Caplan et
25
al, the second largest subclass of respiratory events
leading to claims was esophageal intubation (18% of
respiratory events). In the claims for esophageal intubation events in which postintubation breath sounds
were documented, Caplan et al25 found that 48% documented the intubation as tracheal. Cheney2 credited
this study with guiding the ASA Committee on Standards to require end-tidal carbon dioxide verification
of endotracheal intubation. Subsequent claims attributed only 7% of the respiratory event–related death or
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brain damage outcomes to esophageal intubation.7,18
Miller29 pointed out that none of the claims data
reflected practice since widespread use of the laryngeal mask airway, which was expected to further
decrease frequency of these incidents. Cheney17,19
reported that end-tidal carbon dioxide verification of
intubation was inversely correlated with death or
brain damage when esophageal intubation did occur.
The third largest subclass of respiratory events
leading to claims was difficult tracheal intubation
(17%).25 Practice guidelines for management of the
difficult airway were first published in 1993.18,19,30 In
an evaluation of their effectiveness, Peterson et al31
found that after publication of the guidelines, difficult
airway claims associated with death or brain damage
during induction decreased from 62% to 35%. Nevertheless, for the same period, Moody and Kremer32
reported that 27% of respiratory events in CRNArelated claims had no documented airway assessment;
so, simple practice improvements could still reduce
risk associated with difficult airways. Peterson et al31
also found that death or brain damage was correlated
with development of an airway emergency, as were
persistent intubation attempts during an airway emergency. They recommended development of additional
management strategies for difficult airways encountered during maintenance, emergence, or recovery
from anesthesia to complement the apparently successful induction algorithm. The most recent practice
guideline conceded that the literature did not adequately address extubation strategies for the difficult
airway.33
Aspiration was considered the primary or secondary damaging event in 3.5% of all claims.34 Of these
events, 67% occurred during induction, and 11% of
these claims showed documented cricoid pressure. Of
the aspiration claims, 60% were associated with an
outcome of death or brain damage compared with
43% of nonaspiration claims. Nevertheless, Cheney34
concluded, “aspiration of gastric contents is not a
major liability hazard for the anesthesiologist.” These
data also reflect practice before the widespread use of
the laryngeal mask airway.
In research by Domino35 and Domino et al,36 airway trauma was identified in 6% of the ASA-CCP
claims. Of these claims, 38% showed difficult intubation to be a contributing factor, and in 9%, the patient
sustained brain damage or died. Sites of injury
included the larynx (34%), pharynx (17%), esophagus (16%), trachea (14%), and temporomandibular
joint (10%). Laryngeal injury was usually associated
with appropriate care (83% of these cases) and most
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269
often resulted in vocal cord paralysis (31% of these
cases). Retropharyngeal abscess and/or mediastinitis
developed in 61% of the claims for perforation injury
of the esophagus or pharynx, and 31% of these claims
showed death as the ultimate outcome.36 Elderly
women were represented in a greater percentage of
esophageal injury claims compared with other claims,
although no mechanism was apparent.36 In only 51%
of the claims for perforation injury were there signs of
pneumothorax and/or subcutaneous emphysema;
consequently, the researchers recommended alerting
the surgeon and patient to watch for signs and symptoms of mediastinitis or retropharyngeal abscess when
intubation is difficult or initially esophageal.36
• Nerve injury. Since 1990, 17% of all claims in the
ASA-CCP database related to a nerve injury outcome.37 In all data collected in the ASA-CCP, ulnar
nerve injuries were the most commonly claimed nerve
injury (25%), followed by injuries to the brachial
plexus (19%); 86% of claimed ulnar nerve injuries
were sustained during general anesthesia.37 Although
ASA-CCP research reported that these peripheral
nerve injuries seemed to occur in the presence of adequate positioning and padding,37,38 AANA data
showed the use of padding was undocumented in 57%
of nerve injury claims, patient positioning was undocumented in 55%, and improper patient positioning
was identified in 36%.39 Cheney et al38 compared the
claims reflecting injuries since 1990 and found that
spinal cord injury claims had surpassed ulnar nerve
injury claims and were associated with neuraxial
blocks in anticoagulated patients and with blocks for
chronic pain.
• Central venous catheter complications. Recent studies of ASA-CCP data showed an increase in the proportion of claims related to central venous catheter
(CVC) complications from 13.5% before 1990 to
16.5% before 2004 and an increase in CVC-related
claims with an outcome of death (42% to 47%).40-42 Of
the CVC-related death claims before 1990, 75% were
due to cardiac tamponade or vascular injury.40 For all
claims before 2004, events by proportion of CVCrelated claims included the following: wire or catheter
embolus, 18%; cardiac tamponade, 15%; carotid artery
puncture or cannulation, 15%; hemothorax, 14%;
pneumothorax, 13%; and pulmonary artery rupture,
6%. These events were thought to be preventable in at
least 45% of the claims by implementing the following:
(1) ultrasound-guided catheter placement, (2) transduction of a pressure waveform to confirm cannulation of a vein, (3) chest radiograph, or (4) interval or
continuous monitoring of a pressure waveform.41,42
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• Burns. Kressin43 analyzed burn outcome claims in
the ASA-CCP database. Of the claims, 2% were for burn
injuries and were attributed to the following events:
intravenous (IV) bags or bottles, 35% of burn claims;
warmers, 23%; cautery fires, 19%; cautery burns without fire, 12%; lasers in the airway, 2%; magnetic resonance imaging at the site of pulse oximetry, 2%;
retractors, 1%; defibrillator paddles, 1%; and electrocardiographic leads, 1%. A 1994 analysis of the data
showed 64% of burn claims were related to the use of
heated IV bags or bottles as warmers,44,45 but claims
since 1994 showed that IV bags or bottles contributed to
only 12% of burn claims.43 The majority of cautery fires
occurred to the face during plastic surgery under monitored anesthesia care.43 Almost all (93%) of claimed
burn outcomes were temporary or nondisabling.43
• Postoperative visual loss. Recognition of the prevalence of perioperative ischemic optic neuropathy
through closed claims data analyses led to the creation
of the Postoperative Visual Loss Registry in 1999 for
anonymous physician submissions.46 By using Postoperative Visual Loss Registry data, Lee47,48 found that
81% of submissions were related to ischemic optic
neuropathy and correlated with large blood loss, prolonged hypotension, prone positioning, and vasoocclusive disease. Central retinal artery occlusion
accounted for an additional 13% of submissions and
was correlated with direct pressure on the globe,
emboli, and low retinal perfusion pressure. Of
patients sustaining ischemic optic neuropathy, 39%
recovered at least partial sight, whereas none of the
patients sustaining central retinal artery occlusion
recovered. Eye loss due to regional block is addressed
in the Special settings or circumstances section.
• Intraoperative awareness. According to ASA-CCP
data, 2% of all claims involved intraoperative awareness.7,49,50 Of these cases, 75% resulted in recall of
events during anesthesia. Of these, care was judged
substandard in 42% and was attributed to inadequate
anesthesia: failure to turn on the agent vaporizer,
vaporizer malfunction, or failure to anesthetize sufficiently during induction.49,50 The remaining 25% of
these cases resulted in inadvertent paralysis of a conscious patient. Care was judged substandard in 94% to
96% of these cases and was attributed to medication
error: an infusion of succinylcholine from an unlabeled, misread, or mislabeled bag or a bolus of succinylcholine from a mislabeled or misread syringe.49,50
Grinblat51 advised providers to allow patients reporting anesthesia awareness to discuss their experiences
and feelings fully, to document the patient’s report
thoroughly, and to provide support.
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• Medication errors. Bowdle52 found 4% of claims
related to medication administration errors with no
change in frequency over time. The most common
errors were incorrect dose (31%), substitution of the
incorrect drug (24%), and administration of a drug
not intended to be given (17%). The most common
medications were succinylcholine (17% of medication
claims), usually resulting in awareness with paralysis
or prolonged blockade, and epinephrine (8%), usually
resulting in death or major morbidity. Of the medication claims, 58% were associated with death or major
morbidity.
• Gas delivery device problems. Of all ASA-CCP
claims, 2% were related to problems with the anesthesia machine.12,53 Of these claims, 75% documented
misuse, and the rest were machine failures. Caplan et
al12 found the problem related to the breathing circuit
in 39% of the gas delivery claims and to the vaporizers, ventilators, or oxygen supply lines or tanks in
49%. Although the primary anesthetist was responsible for the reported misuse in 70% of the applicable
claims, in 30% of misuse claims, ancillary personnel
crossed supply lines at the machine, crossed central
supply lines, delivered the wrong central tank, flushed
central oxygen lines with nitrogen without notification, installed a 1-way valve backward, or applied 50
psi oxygen to an endotracheal tube postoperatively.
Misconnections and disconnections, often associated
with barotrauma or pneumothorax, accounted for one
third of the claim events. All vaporizer problems that
led to brain damage or death occurred before 1985;
later claims resulted in delivery of less agent than
intended and consequent intraoperative awareness.12
Recommendations for prevention included redesign
of the breathing circuit, strategies and education for
ancillary personnel, and ensuring that appropriate
monitors are functioning at all times.12
• Special settings or circumstances. As anesthetic use
outside of the operating room has increased, so has
concern for liability and patient safety in these settings. Monitored anesthesia care targets a level of
sedation between that of conscious sedation and general anesthesia54 and was represented in the claims for
death outcomes at the same rate as general and
regional anesthesia.55 Precipitating events were categorized as respiratory (26%), unknown (23%), cardiovascular (10%), and IV complications (7%).55
Ambulatory surgery–related claims composed 23%
of the total ASA-CCP data.56 Posner56 found that these
claims had a higher percentage of monitored anesthesia care or regional anesthesia, regional anesthesia–related events, and temporary or nondisabling
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injuries but a lower percentage of respiratory events.
By contrast, office-based anesthesia, which composed
0.3% of all claims, reflected a higher percentage of
death, respiratory events, preventable outcomes, and
drug errors or reactions.57 Neither study addressed
the use or availability of resuscitation equipment or
the success of resuscitation efforts.
Zeitlin58 reported that 7% of closed claims events
developed in the postanesthesia care unit. Of these
claims, 75% had death or brain damage as an outcome, and 39% were thought preventable with pulse
oximetry or capnometry compared with 29% of other
claims. This early study probably reflected few data
after basic monitoring became the standard of practice.
The proportion of claims related to nonoperative
pain management (NOPM) has increased during the
last 3 decades to 10% of all claims in the 1990s.59-61
Inadequate follow-up care was identified as a contributing factor in 24% of NOPM claims (16% of all
other claims),61 and 40% of NOPM claims were due to
epidural steroid injury.60 Outcomes included nerve
injury or paralysis or paraplegia (23% of all NOPM
claims), pneumothorax (21%), brain damage or death
(9%), postdural puncture headache (8%), no pain
relief (8%), meningitis (6%), infection at the injection site (4%), and retained catheter (3%).60
Kalauokalani61 also found that the anesthetic record
was inadequate in 74% of NOPM claims (50% of all
other claims).
Regional anesthesia claims were related to neuraxial block cardiac arrest (30% of regional anesthesia
claims), pain management (23%), and intravascular
injection (10%).62 Although death-related claims were
relatively low, at 2.6%, eye loss accounted for 22% of
the claims of permanent injury related to a regional
anesthetic.62 Lee et al63 reported an increase in the
percentage of permanent injury due to eye blocks
from 2% of all regional anesthesia claims in the 1980s
to 7% in the 1990s.
When compared with other claims, obstetric event
claims had death as an outcome less frequently:
maternal deaths composed 19% to 22% of all obstetric
claims, neonatal deaths composed 27%, and newborn
brain damage composed 14% to 22%.21,64-66 The most
common event related to maternal death was failure to
secure an airway.21 When compared with nonobstetric
claims, more patients who are obese are represented in
obstetric claims (25% vs 19%), and this may contribute to difficult intubation.66 Commonly reported
outcomes were maternal headache, pain, back pain,
and emotional distress (47% of all obstetric claims)
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271
and were correlated with patient dissatisfaction with
care and more frequent use of regional anesthesia.64,65
The researchers noted the importance of anticipating
and preparing for airway difficulties and using protocols specific to the obstetric population, which consider the concurrent needs of mother and child.21,64-66
Patients younger than 16 years were represented in
10% of all claims.67 Morray et al67 found these claims
to have a higher percentage of death outcomes, 50%
compared with 35% in adults, and a higher percentage
of respiratory events, 43% vs 30%. A more recent
study, however, found only 25% of the pediatric
claims from the 1990s were associated with respiratory events and that this decrease coincided with a
drop in monitor-preventable events.68 Cardiovascular
events represented 27% of pediatric claims in the
1990s.67 Recognition of this led to creation of the
Pediatric Perioperative Cardiac Arrest Registry in
1994, which is composed of anonymous physician
submissions of cases requiring chest compressions or
resulting in death during anesthesia or in the
postanesthesia care unit.6,7,68,69 Analysis of Pediatric
Perioperative Cardiac Arrest Registry data showed
that 67% of cardiac arrests occurred during maintenance anesthesia, 56% of events were attributable to
cardiovascular causes (eg, electrolyte imbalance, fluid
therapy, hemorrhage, and cardiopulmonary bypass),
42% of patients had no discernible precipitating
injury, and 43% of patients died within 24 hours.70,71
Jimenez68 also reported that medication events were
related to wrong dose in 53% of relevant claims,
which might be due to relatively complex pediatric
dosing.
Sharar72 found that 4.8% of claims between 1987
and 1999 involved trauma anesthesia care. Of these,
72% involved emergency anesthesia and surgery and
51% of the patients were classified as ASA physical
status III to V. Nontrauma claims, by contrast,
involved emergency anesthesia in only 18% of the
claims, and 34% of patients were classified as ASA
physical status III to V. Nevertheless, when compared
with nontrauma claims, trauma claims were not significantly different in the proportion of claims for
aspiration, brain damage, difficulty of intubation,
intraoperative awareness, standard of care, or adequacy of records. Sharar72 found more trauma claims
associated with an outcome of death (40.3% compared with 23.4%).
Consent was identified as a liability issue in 1% of
the ASA-CCP database claims.73,74 For these claims,
the provider failed to honor a patient request, such as
a request that no medical resident be involved, or
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failed to discuss a specific complication or change in
anesthesia plan.
Discussion
• Limitations. Closed claims data do not necessarily
reflect the frequency of occurrence of outcomes or
events. Some injured patients do not file claims, but
some patients who were not injured do file claims.2
Furthermore, these databases contain no data on the
total number of anesthetics delivered, so they cannot
be used to calculate or compare risk.2,10,66 Nevertheless, researchers seem challenged to word conclusions
in a way that does not overstate the findings: “The
1990s present a profile of fewer claims for death and
brain damage and fewer respiratory system mishaps
than preceding decades. This improved injury profile
is reflected in fewer payments.”4 Similar statements
were made by Caplan7 and by Cheney34 who said:
“This suggests that strategies for prevention of aspiration in the OB patient were incorporated into clinical
practice in the 1980s.” Decreased risk cannot be concluded from closed claims data. Surprisingly, the following passage from Ross75(p188) followed a lengthy
explanation of closed claims limitations with regard to
risk estimation:
Setting aside these limitations, the Closed Claims database does
provide valuable information. The data allow comparison of
claims made in obstetrical anesthesia cases versus those in other
anesthesia specialties, looking for differences in patterns of
injury or outcomes. One is also able to answer a number of
important questions such as: Which injuries are most common
in obstetrical anesthesia?
The use of parametric statistics is only appropriate
when a sample is taken randomly. Clearly, closed
claims data do not adhere to this assumption, and
only nonparametric tests should be used. Although
most research reported chi-square or other nonparametric comparisons, Cheney2 used the Z-test, a parametric statistic.
Retrospective data cannot be used to test hypotheses; therefore, no cause and effect conclusions can be
drawn from closed claims data. Again, researchers’
conclusions could give a misimpression that causality
had been elucidated: “Research findings reported here
demonstrate that incomplete preinduction activities
can contribute to damaging events and adverse outcomes in anesthesia.”32 The finding of incomplete
preinduction activities for some cases with adverse
outcomes says nothing about cases with positive outcomes and whether they were associated with complete preinduction activities.
Because claims for which a lawsuit was filed eventually amassed considerable documentation, these
cases were more likely to meet the completeness cri-
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terion for inclusion in a database,9 which could exacerbate problems of systematic sampling bias. In addition, the recognized lag time of 6 months to 10 years
increases the risk of premature analysis, although the
timing of the study did not always accommodate this
limitation; for example, Cheney62 published “Highseverity injuries associated with regional anesthesia in
the 1990s” in 2001.
Reviewers necessarily experienced some hindsight
bias.3 Although reliability was reportedly “within the
accepted range” for the ASA-CCP data,2 Caplan and
Posner76 found that the judgment of appropriateness
of care is subjective and influenced by a finding of permanent injury. Specifically, the researchers provided
case details to reviewers but changed the outcome
from temporary injury to permanent injury. Reviewers
were twice as likely to find care less than appropriate
when told the outcome was permanent injury. Posner
et al77 also found that reviewers agreed on the appropriateness of care for 62% of cases and disagreed for
38%; chance agreement was expected to occur 40% of
the time. Bias should also be expected in the original
anesthetic records and other case documentation
because their preparers cannot be impartial.3,10
Failure to recognize these limitations may contribute to a perception that anesthetic risk has
decreased by at least an order of magnitude during the
last 2 decades.78(p32) In response to claims of extreme
rarity of anesthetic incidents and as an illustration of
the limitations of nonstandardized methods and nonrepresentative sampling, Lagasse79 undertook a literature review study of published anesthesia-related perioperative mortality rates. Contrary to the Institute of
Medicine’s report78 that anesthesia deaths have
decreased from 2 in 10,000 in the 1980s to 1 in
200,000 to 300,000 at the time of the report, Lagasse79
found the following:
1. Anesthesia-related mortality as determined by
peer review had been stable during the previous
decade at 1 in 13,000.
2. Incidents for patients classified as ASA physical
status I through V averaged 1 in 500 anesthetics.
3. The wide range reported in the literature
reflected differences in operational definitions, reporting sources, and risk stratification.
• Practice changes. According to Cheney,2 the 1990
study by Caplan et al25 compelled the ASA Committee
on Standards to require (1) intraoperative and
postanesthesia pulse oximetry,26 (2) end-tidal carbon
dioxide verification of endotracheal intubation,25 and
(3) difficult airway practice guidelines.30,33
According to Cheny6 and Caplan,7 a cooperative
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effort between the ASA-CCP and the Quality Assurance Committee of the American Academy of Pediatrics established the Pediatric Perioperative Cardiac
Arrest Registry in 1994 in response to research by Morray et al67 and Morray.69 Similarly, the Postoperative
Visual Loss Registry, another ASA-CCP cooperative
effort, complements eye injury closed claims data.46
Research also showed that a considerable number
of malpractice actions against anesthesiologists were
unfounded and that providers are at risk for litigation
in the absence of deviation from standards of care.80,81
Nevertheless, over time, fewer claims have resulted in
payments to plaintiffs.4,82 There have been significant
decreases in liability premiums for anesthesiologists
during the last 2 decades,2,18,83 although that trend
seems to be reversing.14,84-86
Summary and further research directions
These studies suggest the following:
1. Errors in judgment and performance occur and
can have serious consequences.
2. Monitors and alarms are invaluable, particularly
end-tidal carbon dioxide detectors, pulse oximeters,
oxygen analyzers, and ventilator disconnect alarms.
3. Anesthetists must be familiar with and use the
alarms and recommended preuse equipment checks.
4. Incidents detected with noninvasive blood pressure measurement are late in development.
5. A stethoscope should be available to clarify
ambiguous or confusing information. 10 Other
researchers have made recommendations for building
on these studies:
1. Identification of ways to use the data as an “early
warning system,”83
2. A prospective study comparing occurrence of
spinal cord injury in vascular surgery patients requiring systemic heparinization with and without neuraxial block,2
3. Identification of the mechanism for the possible
increased risk of airway injury in elderly women,36
4. Additional study of the suggested relationship
between eye injury and independent CRNA practice,3
5. Collaborative research efforts between physician
and nurse anesthetists,21
6. Further investigation of cognitive issues such as
the pursuit of a plan in direct conflict with clinical
evidence (eg, continued and repeated attempts to
intubate), the interactions of multiple factors that culminate in an adverse event, the effects of stress and
conflicting goals on the occurrence of critical events,
and the analysis of narrative portions of the AANA
database,21
7. Development of standardized assessment and
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perioperative event forms to maximize available information, establish appropriate denominators for risk
estimation, test cause and effect hypotheses, and tease
apart outcomes due to patient predisposition or risk
factors,87
8. Availability and use of resuscitation equipment
for office-based anesthesia and the effect on success of
resuscitation, and
9. An updated examination of postanesthesia care
unit claims.
The usefulness of closed malpractice claims
research is evident. The insights gained from examining these data have been and will continue to be
important contributions toward ensuring patient
safety. At a time when healthcare reform proposals
legitimately embrace improving patient safety, the
profession is well served by those who work to extract
as much as possible from closed claims data. Care
must be taken not to overstate the findings, however,
because these data are not appropriate for calculation
or comparison of risk. Future research would ideally
include greater interdisciplinary collaboration with
unwavering focus on the common goal of providing
the safest care possible.
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AUTHOR
Meghan G. MacRae, RN, PhD, is a student at the University at Buffalo
State University of New York Nurse Anesthetist Program, Buffalo, NY.
Email: [email protected]
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